Multidecadal climate variability in Brazil's Nordeste during the last 3000 years based on speleothem isotope records

Author(s):Show less -

Novello, Valdir F. ^[1] ; Cruz, Francisco W. ^[1] ; Karmann, Ivo ^[1] ; Burns, Stephen J. ^[2] ; Stirkis, Nicolas M. ^[1] ; Vuille, Mathias ^[3] ; Cheng, Hai ^{[4, 5]} ; Edwards, R. Lawrence ^[5] ; Santos, Roberto V. ^[6] ; Frigo, Everton ^[7] ; Barreto, Eline A. S. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Geociencias, BR-05508080 Sao Paulo - Brazil

^[2] Univ Massachusetts, Dept Geosci, Amherst, MA 01003 - USA

^[3] SUNY Albany, Dept Atmospher & Environm Sci, Albany, NY 12222 - USA

^[4] Xi An Jiao Tong Univ, Inst Global Environm Change, Xian 710049 - Peoples R China

^[5] Univ Minnesota, Dept Geol & Geophys, Minneapolis, MN - USA

^[6] Univ Brasilia, Inst Geociencias, Brasilia, DF - Brazil

^[7] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508080 Sao Paulo - Brazil

• Document type: Journal article
• Source: Geophysical Research Letters; v. 39, DEC 12 2012.
• Web of Science Citations: 43

Abstract

We present the first high resolution, approximately similar to 4 years sample spacing, precipitation record from northeastern Brazil (hereafter referred to as `Nordeste') covering the last similar to 3000 yrs from Th-230-dated stalagmites oxygen isotope records. Our record shows abrupt fluctuations in rainfall tied to variations in the intensity of the South American summer monsoon (SASM), including the periods corresponding to the Little Ice Age (LIA), the Medieval Climate Anomaly (MCA) and an event around 2800 yr B.P. Unlike other monsoon records in southern tropical South America, dry conditions prevailed during the LIA in the Nordeste. Our record suggests that the region is currently undergoing drought conditions that are unprecedented over the past 3 millennia, rivaled only by the LIA period. Using spectral, wavelet and cross-wavelet analyses we show that changes in SASM activity in the region are mainly associated with variations of the Atlantic Multidecadal Oscillation (AMO) and to a lesser degree caused by fluctuations in tropical Pacific SST. Our record also shows a distinct periodicity around 210 years, which has been linked to solar variability. Citation: Novello, V. F., et al. (2012), Multidecadal climate variability in Brazil's Nordeste during the last 3000 years based on speleothem isotope records, Geophys. Res. Lett., 39, L23706, doi: 10.1029/2012GL053936. (AU)

• FAPESP's process: 06/06761-0 - Late quaternary paleoclimate in Brazil from oxygen and carbon isotope ratios on speleothems
• Grantee: Francisco William da Cruz Junior
• Support type: Research Grants - Young Investigators Grants